1.给定一个字符串，请你将字符串重新编码，将连续的字符替换成“连续出现的个数+字符”。比如字符串AAAABCCDAA会被编码成4A1B2C1D2A。（有问题）

<?php
function string($string=''){
  $arr = array_count_values(str_split($string));
  $string_num = '';
  foreach ($arr as $k => $v) {
        $string_num .= $k . $v;
  }
  return $string_num;
}
echo string('AAAABCCDAA');